Organofunctional silanes, such as aminoalkyl-, mercaptoalkyl-, phosphinoalkyl-, and the like, represent an important class of silicon compounds. These silanes find extensive application in commercial products such as coupling agents, adhesion promoters and crosslinkers, inter alia. These compounds can also be used to functionalize siloxane polymers, thereby enhancing their advantageous properties in various silicone applications.
A number of existing methods for preparing organofunctional silanes depend on multi-step synthetic routes that suffer from poor yield and waste problems in one or more of the steps. For example, preparation of acid chloride functional silanes requires a two-step process wherein a carboxy acid-functional silane is first synthesized and this, in turn, is reacted with thionyl chloride. The latter compounds find utility in the preparation of silicone-organic copolymers and organofunctional silanes that can be derived from their well-known reactivity. There is, therefore, a need for improved methods which can provide various functional silanes in an efficient and economical manner.
A simple method for preparing carbinol-functional siloxanes has been disclosed by Burns et al. in U.S. Pat. No. 5,290,901. In this procedure, a cyclic silyl ether is reacted with an organosiloxane or organosiloxane resin. The reactivity of such a cyclic silyl ether was studied by R. J. P. Corriu et al. (Journal of Organometallic Chemistry, 114, 21-33 (1976)) and these authors disclose the reaction of an oxasilacyloalkane with acetyl chloride to form an acetate-functional chlorosilane.
However, there is no expectation that the outcome of the reaction of a cyclic silyl ether with any given halogen-functional component, other than the simple acyl halide illustrated by Corriu et al., could be predicted without experimentation. Thus, neither the publication by Corriu et al. nor any other prior art know to applicants teaches the reaction of such cyclic silyl ethers with the particular halogen-functional compounds of the present invention to prepare functional halosilanes.